Search

Surfactant-modified CeO2@TiO2core–shell nanostructure catalysts were prepared by coprecipitation with the addition of sodium dodecyl sulfonate (SDS), and their catalytic oxidation of dichloromethane (DCM) was studied. A 90% DCM conversion efficiency is obtained at 300 °C with the CeO2@TiO2SDS catalyst, and its catalytic stability in the 55 h test period is better than that of Ce/TiO2and CeO2@TiO2. Based on the characterization of CeO2@TiO2SDS, the dispersion of active components is promoted due to the inhibition of crystal growth with the introduction of SDS. The improvement of surface acidity and redox capacity is beneficial to the enhancement of catalytic activity. The higher adsorbed oxygen content on the surface of the CeO2@TiO2SDS catalyst is responsible for the better catalytic stability. Generally, a novel method was developed to design catalytic oxidation catalysts for the treatment of chlorinated volatile organic compounds in future applications.

A CoCe/ZSM-5 catalyst was prepared by ultrasonic-assisted impregnation for the catalytic combustion of toluene. To study the effect of Na+on catalytic performance of CoCe/ZSM-5 catalysts, a series of different Si/Al ZSM-5 zeolites and catalysts doped with Na were synthesized. The experimental results show that 0.71 wt% Na+can inhibit active growth, generate more active small crystal grains, and promote improvement of the catalytic activity by the grain boundary segregation block mechanism, and the catalyst with 0.71 wt% of Na shows toluene conversion of 90 vol% at 250 °C. Over 0.71 wt% of Na+content will neutralize the acid centre of the catalyst, lowering the specific surface area of the catalyst and resulting in a gradual decrease in the catalytic activity.

Aberrant DNA methylation is a distinguishing feature of cancer. Yet, how methylation affects immune surveillance and tumor metastasis remains ambiguous. We introduce a novel method, Guide Positioning Sequencing (GPS), for precisely detecting whole-genome DNA methylation with cytosine coverage as high as 96% and unbiased coverage of GC-rich and repetitive regions. Systematic comparisons of GPS with whole-genome bisulfite sequencing (WGBS) found that methylation difference between gene body and promoter is an effective predictor of gene expression with a correlation coefficient of 0.67 (GPS) versus 0.33 (WGBS). Moreover, Methylation Boundary Shift (MBS) in promoters or enhancers is capable of modulating expression of genes associated with immunity and tumor metabolism. Furthermore, aberrant DNA methylation results in tissue-specific enhancer switching, which is responsible for altering cell identity during liver cancer development. Altogether, we demonstrate that GPS is a powerful tool with improved accuracy and efficiency over WGBS in simultaneously detecting genome-wide DNA methylation and genomic variation. Using GPS, we show that aberrant DNA methylation is associated with altering cell identity and immune surveillance networks, which may contribute to tumorigenesis and metastasis.

A Reynolds‐Averaged Navier‐Stokes (RANS) flow solver with a Volume of Fluid (VOF) surface capturing scheme is used to investigate wave breaking and blocking due to strong opposing currents. The Shear Stress Transport (SST) k−ωmodel is modified in order to capture the turbulence properly. The unique capability of the RANS‐VOF model allows us to reveal the distinct features of current‐induced wave breaking and blocking. The limiting wave steepness at breaking onset is reduced considerably by the opposing current from the Stokes' limit for stationary waves. Although the wave height grows faster before breaking under a more rapidly varying current, the maximum height at the breaking onset remains almost the same. The locations of incipient breaking are slightly shifted downstream/upwave by the increased current gradient. It was found that the wave radiation stress alters the mean water level by competing with the pressure gradient arising from the current‐induced surface tilting. The wave set‐down and set‐up is more pronounced for more intensive breakers occurring under a larger incident wave and current gradient. Our model results indicate an undertow‐like change to the current profile due to wave breaking. The turbulence and vorticity generated by the current‐induced breaking wave persist and are advected downstream and interact with those generated by the following wave and current. Current‐induced breaker has a limiting wave steepness of ak= 0.3, much smaller than that for a Stokes wave at deep waterWave set‐down and set‐up exist by competing with the pressure gradient caused by the current‐induced surface tiltingTurbulence and vorticity generated by breaking wave are advected downstream by current, and interact with those generated by the following wave and current

MicroRNAs (miRNAs) are a class of endogenous non-coding RNAs with regulatory functions. Traditionally, miRNAs are thought to play a negative regulatory role in the cytoplasm by binding to the 3′UTR of target genes to degrade mRNA or inhibit translation. However, it remains a challenge to interpret the potential function of many miRNAs located in the nucleus. Recently, we reported a new type of miRNAs present in the nucleus, which can activate gene expression by binding to the enhancer, and named them nuclear activating miRNAs(NamiRNAs). The discovery of NamiRNAs showcases a complementary regulatory mechanism of miRNA, demonstrating their differential roles in the nucleus and cytoplasm. Here, we reviewed miRNAs in nucleus to better understand the function of NamiRNAs in their interactions with the enhancers. Accordingly, we propose a NamiRNA–enhancer–target gene activation network model to better understand the crosstalk between NamiRNAs and enhancers in regulating gene transcription. Moreover, we hypothesize that NamiRNAs may be involved in cell identityor cell fatedetermination during development, although further study is needed to elucidate the underlying mechanisms in detail.

Abstract: A two phase flow CFD model has been developed for 2D spilling breaking wave simulations. A mass conservative level set method similar to Olsson and Kreiss [Olsson E, Kreiss G. A conservative level set method for two phase flow. J Comput Phys 2005;210(1):225–46] is implemented for capturing the air–water interface. The solver is discretised using a finite volume method based on a curvilinear coordinate system. A fully implicit fractional step method is used to advance simulations in time. The solver has been tested and validated by repeating benchmark results of dam breaking simulation and travelling solitary wave simulation. Finally, we employ this solver to simulate spilling breaking waves in the surf zone. Our results show that surface elevations, the location of the breaking point and undertow profiles can generally be well captured. We have also found that temporal and spatial schemes may have significant impacts on computational results. [Copyright &y& Elsevier]

The present paper aims to clarify the mechanism of infragravity wave (IGW) energy amplification over nearshore shoals reported in recent studies. Wave transformation and energy transfer between short waves (SWs) and IGWs were investigated using SWASH model for nonbreaking random waves propagating over trapezoid shoals with different bottom slopes. It was found that the time lag of IGWs relative to SW groups is the major mechanism for energy transfer from SWs to IGWs and the amplification of IGW energy over all segments of the shoal. The time lag is generated on the front slope and enlarged on the plateau of the shoal, decreases on the rear slope with higher decreasing rates on milder slopes. Over the rear slope, the evolution of IGWs depends on the relative importance of deshoaling and nonlinear energy transfer. It was found that nonlinear energy transfer dominates over the rear slope gentler than 1/60, causing the IGW energy to increase over the first half of the deshoaling process and decrease over the second half whereas deshoaling dominates for steeper rear slope and the IGW energy decay over the whole slope. It is demonstrated numerically and theoretically that the shoals with gentler bottom slopes amplify the IGW energy more effectively by providing longer distance for nonlinear energy transfer to build up. The persistent nonlinear energy transfer on the plateau indicates the important role of wave spatial evolution history in the subsequent IGWs evolution. Strong free IGWs were detected on leeward of the shoal, possibly due to release of topography‐induced additional bound IGWs. Wave spatial evolution history has significant effects on the subsequent evolution of infragravity wavesInfragravity wave energy is significantly amplified in the direction of wave propagation by a near shore shoalShort waves continually transfer energy to infragravity waves when propagating across the shoal even in the deshoaling zone